Lactate to Pyruvate Ratio, Whole Blood
Ordering Recommendation

When considering pyruvic acid testing, this is the preferred test.  This test reports concentrations for lactate, pyruvate, and the L:P ratio on the same specimen.

Quantitative Enzymatic
1-2 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Patient should be fasting and at complete rest. Patient should avoid any exercise of the arm or hand before or during collection. Draw the specimen without the use of a tourniquet or within three minutes of applying the tourniquet, but before releasing the tourniquet. 
Green (Sodium or Lithium Heparin). 
Specimen Preparation
If whole blood is collected in a syringe, transfer immediately to green (sodium or lithium heparin) tube before preparing specimen.
1) Immediately after blood is drawn, add exactly 1 mL whole blood to a chilled pyruvate collection tube containing 2 mL 8 percent (w/v) perchloric acid (ARUP supply #16567) available online through eSupply using ARUP Connect™ or contact Client Services at (800) 522-2787.
2) Mix well for 30 seconds then place in an ice bath for 10 minutes.
3) Centrifuge for 10 minutes at 1500 x g.
4) Decant 2 mL supernatant to an ARUP Standard Transport Tube and freeze. (Min: 1 mL) 
Storage/Transport Temperature
Unacceptable Conditions
Ambient: Unacceptable; Refrigerated: 2 days; Frozen: 4 weeks 
Reference Interval
Available SeparatelyComponentsReference Interval
NoLactate0.31-2.00 mmol/L
NoPyruvate0.030-0.107 mmol/L
NoL:P RatioNot Applicable

Interpretive Data
The blood lactate to pyruvate (L:P) ratio is used to distinguish between pyruvate dehydrogenase deficiency and other causes of congenital lactic acidosis. In conjunction with an elevated lactate, an L:P ratio greater than 30 suggests inherited disorders of the respiratory chain complex or tricarboxylic acid cycle disorders. In conjunction with an elevated lactate, an L:P ratio less than 25 suggests a defect in pyruvate metabolism. An artificially high L:P ratio can be observed in acutely ill individuals. Abnormal concentrations of lactate, pyruvate, and the L:P ratio are not diagnostic for any single disorder and must be interpreted in the context of the individual's clinical presentation and other laboratory studies.

Statement B: Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

If addition to perchloric acid is delayed, lactate concentration of whole blood increases by approximately 30 percent after 30 minutes, 50 percent after 1 hour, and 75 percent after 2 hours at room temperature. If less than 1 mL of blood is added to collection tube, pH of the supernatant will be too low for testing.
Hotline History
Component Test Code*Component Chart NameLOINC
2007936Lactic Acid32693-4
2007937Pyruvic Acid14121-8
2007938Lactate to Pyruvate Ratio2550-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please view this test within the Laboratory Test Directory found at
  • Lactate Pyruvate Ratio
  • LP Ratio
  • Pyruvate (Pyruvic Acid)